Pharmaceutical containers for liquids have a piercable closure member such as a disc or stopper which is formed of rubber or other elastomeric materials, held in place with a metal cap. Such caps generally have an inner removable disc which is detachably secured to the outer annular top portion by fractional or frangible bridges. By lifting off the center disc portion which is attached to an outer cap, a portion of the stopper is made available for piercing with syringes or intravenous spikes.
One system for employing such caps with a cover which is attached to the outer annular portion of the cap and which may be removed by the thumb is shown in U.S. Pat. No. 3,071,274. Still another alternative technique is the use of a tear-off cap which provides a hinged central portion at the top of the cap to provide a grip for tearing off the cover over the stopper and around the top of the container. A hypodermic syringe and needle is employed often to add or remove fluids to the container and it is desirable to be able to expose the rubber stopper portion of the closure by simply removing the overcap.
Even though a number of systems have been designed which employ a thumb removable overcap, none of them have been found to be absolutely ideal under certain circumstances of use. Specifically, even though the rubber stopper may be sterilized during manufacture, and even though the overcap may keep the portion of the stopper which is to be penetrated by the syringe needle free from contamination, there is always the concern that once the overcap has been removed, the exposed rubber stopper may be contaminated prior to use. For example, in the very process of removing the cap with the thumb, the thumb itself could come in contact with the exposed surface of the rubber stopper. This is not a problem if the user is wearing sterilized gloves, although even in that case the gloves may become contaminated merely by picking up the bottle. Accordingly, it is conventional in laboratories and doctors' offices, for example, to swab the surface of the exposed rubber stopper prior to the penetration of the stopper with a sterilized needle.
Often times, when the overcap is removed and the frangible bridges are fractured, small portions of metal remain exposed. At the very least, the swabbing material becomes snagged. If this is unexpected, there is the danger of dropping the vial. At worst, the sterilized gloves or even the hand of the user can be cut on these small sharp pieces.
Accordingly, it is a principle object of the present invention to obviate the possibility of exposed portions of the frangible bridges interfering with the essential step of swabbing the top of the exposed rubber stopper. Other objects will appear hereinafter.